As a U.S. Taxpayer I'm hoping the IRS plugs this hole with regulations (which they are entitled to write "as may be necessary to carry out the purposes of this section, including any such measures as are deemed appropriate to avoid allowing multiple credits or rebates to a taxpayer.")  But honestly at this point I don't know if anyone is minding the store.  They are so far behind on everything else that I doubt they'll be able to give this new code section the attention it deserves.